Microsoft Exchange Server
CVE-2021-26427 — Microsoft Exchange Server Remote Code Execution Vulnerability
Executive Summary
None
Overview
9
CVSS CRITICAL
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
CVSS Vector
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
ATTACK VECTOR
Adjacent_network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Changed
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 7.8
EPSS Score
0.00872
probability of exploitation in the next 30 days
0.54103 percentile - updated 2026-06-21
View on FIRST.org
Affected Products
5 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Microsoft Exchange Server 2013 Cumulative Update 23 | 5007011 (Security Update) |
Important | Remote Code Execution | Yes |
| Microsoft Exchange Server 2016 Cumulative Update 21 | 5007012 (Security Update) |
Important | Remote Code Execution | Yes |
| Microsoft Exchange Server 2016 Cumulative Update 22 | 5007012 (Security Update) |
Important | Remote Code Execution | Yes |
| Microsoft Exchange Server 2019 Cumulative Update 10 | 5007012 (Security Update) |
Important | Remote Code Execution | Yes |
| Microsoft Exchange Server 2019 Cumulative Update 11 | 5007012 (Security Update) |
Important | Remote Code Execution | Yes |
Patches
2 patches
| Article | Type | Restart |
|---|---|---|
5007011 |
Security Update | Yes |
5007012 |
Security Update | Yes |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
National Security Agency (NSA), Andrew Ruddick
References
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